1. Field of the Invention
The present invention relates to the design of electrical circuits, and more specifically to a method and apparatus for applying a desired voltage at a node.
2. Related Art
It is often desirable to apply a desired voltage at a node of an electrical circuit. For example, it may be desirable to apply a specific voltage (termed as a reference voltage) at specific point(s) of an analog to digital converter (ADC). The reference voltage generally specifies a maximum voltage corresponding to the biggest digital code sought to be generated by the ADC. The reference voltage is typically used to perform operations such as converting an analog signal into corresponding digital code and vice versa, as is well known in the relevant arts.
Various approaches are attempted to provide such a desired voltage at a node. In one scenario in which a high load is connected to the node, a buffer is provided between the node and a voltage source. The buffer samples a voltage level provided by the voltage source, and drives the high load. As a buffer provides high impedance, the amount of current drawn from the voltage source is minimized as is generally desirable. One problem with such a buffer based solution is that the buffer may introduce an unacceptable amount of noise in several environments.
Additional/different problems may be presented in other environments in which a desired voltage is to be applied at a node. For example, it may be desirable to apply the same desired voltage level at multiple nodes of a circuit, with each node potentially presenting low, high, and/or different loads. It may be further desirable to share the same voltage source among at least some of the nodes.
In such a scenario, the routing distance (and thus the routing resistance) from the voltage source to each node varies, and the different distances (routing resistance) generally cause corresponding voltage drops. Thus, the voltage level applied at each node may not precisely equal the desired voltage, and the deviation from the desired voltage is generally proportionate to the distance from the voltage source. Such deviations may not be acceptable in several environments.
Accordingly, what is needed is a method and apparatus which applies a desired voltage at a node of an electrical circuit.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.